Because of lightweight properties and easy recycling of olefin thermoplastic elastomers, they have been widely used as elastomers of energy conservation type or resource conservation type, particularly as substitutes for vulcanized rubbers, in the fields of automobile parts, industrial machine parts, electric or electronic parts, building materials and the like.
However, conventional olefin thermoplastic elastomers have drawbacks of poorer elastomeric properties as compared with the vulcanized rubbers, and they have been eagerly desired to be improved in elastomeric properties.
In this connection, olefin thermoplastic elastomers increased in the degree of crosslinking, namely, "perfectly crosslinked olefin thermoplastic elastomers" (e.g., those described in Japanese Patent Publication No. 18448/1980), have been already proposed as the olefin thermoplastic elastomers having improved elastomeric properties.
Though the perfectly crosslinked olefin thermoplastic elastomers are superior to partially crosslinked olefin thermoplastic elastomers in the elastomeric properties, they have problems of poor moldability and bad appearance of its molded product, resulting in limitation on their usage.
The present inventors have earnestly studied to solve such problems as mentioned above, and they have found that a thermoplastic elastomer composition having excellent moldability and capable of providing a molded product of excellent elastomeric properties and good appearance can be obtained by using a specific styrene block copolymer in a specific amount together with materials of the thermoplastic elastomer. Based on this finding, the present invention has been accomplished.